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> I agree that you should be able to generate more power using your legs
> than your arms, but I wonder about power loss in the bicycle drivetrain.
> Also, does anyone have a feel for the efficiency of a propeller versus a
> paddle?
Rowers get more power from the use of ther entire body and the leverage of the oar. no reason why a person pedaling instead of paddling could not get as much power as a bicyclist on a recumbent bike.
> The last question is this: A reasonable figure for the force required to
> move a kayak at 4 knots is about 4 pounds. But even if you could deliver
> twice the usable force with legs and propeller that would only move you at
> 5 knots. So how much speed can be gained from using a more powerful engine
> if we run into hull speed considerations?
When I get out of bed in the morning my legs lift a heck of a lot more than 8 pounds! Climbing stairs i put ALL of my substantial bulk on just one leg at a time. I should think they could do 40 pounds for pretty good stretches, but even if they did just 16, that should get the speed up to around 7-8 knots wouldn't it? Or am I confused here.
Are we comparing the paddling force on the pedaler, or the force that the propellor delivers to the water?
I used to have a 17 pound thrust electric trolling motor, and it was about 1/2 horsepower. Rowing on an ergometer I can get about 1/4 hp. for as long as I care to go. (and at that pace I don't care to go very long!) So by that bit of comparison. perhaps all I am delivering would be aobut 8 pounds of thrust through the propellor, despite my pressure on the pedals being many times that
> I'd think that legs and prop
> would be significantly faster in a short sprint and slightly faster over
> the long haul. But to be a lot faster over the long haul would seem to
> requuire a lot of power.
Those leg muscles are a lot stronger than your arm and chest muscles. If you doubt that, see how far you can walk on your hands!
Pual G. Jacobson
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Guillemot Kayak - High
Performance Wooden Sea Kayak Designs
